The present invention relates to a lower vehicle-body structure of a vehicle, comprising right-and-left side sills extending in a vehicle longitudinal direction at both outward sides, in a vehicle width direction, of a vehicle body, a floor panel connected to the right-and-left side sills, a floor tunnel protruding upward at a central portion of the floor panel, a pair of tunnel side frames extending in the vehicle longitudinal direction along both sides, in the vehicle width direction, of the floor tunnel, and a tunnel member connecting right-and-left lower portions of the floor tunnel.
A conventional lower vehicle-body structure of a vehicle which is disclosed in Japanese Patent Laid-Open Publication Nos. 2008-230435 or 2008-184125, for example, has been proposed in order to achieve the smooth load transmission at a lower portion of a floor tunnel when a collision load is inputted.
The above-described first patent document discloses a floor structure of an automotive vehicle in which there is provided a first panel which interconnects both sides, in a vehicle width direction, of a lower portion of a center tunnel, extending over the center tunnel, and this first panel is joined to lower faces of floor under reinforcements which are arranged at the both sides, in the vehicle width direction, of the lower portion of the center tunnel with bolts.
Further, the first patent document discloses the structure comprising a second panel which is joined to an upper face of the first panel such that its end portions are configured to face to inside wall faces of the floor under reinforcements. According to this structure, when a load is inputted in a vehicle side collision, the end portions of the second panel contact and support the floor under reinforcement, so that deformation of the floor under reinforcement can be prevented properly, which is described in this patent document as an effect.
In the floor structure of the automotive vehicle of the above-described first patent document, however, the end portions of the second panel and the inside wall faces of the floor under reinforcements facing to the second panel's end portions are not directly fixed to each other.
Moreover, the second panel is merely joined to the floor under reinforcements indirectly via the first panel which is joined to the lower face of the floor under reinforcements only with the bolts.
Therefore, there is a concern in the floor structure of the automotive vehicle of the first patent document that their facing face portions slide improperly when receiving a large load, such as a collision load. Thus, there is room for improvement in order to achieve the smoother load transmission at the lower portion of the floor tunnel (center tunnel).
The above-described second patent document discloses a vehicle-body floor portion structure which comprises a pipe member which penetrates a floor tunnel portion and connects right-and-left floor portions and a pair of upper-and-lower brackets which join the pipe members such that an end portion, in an axial direction, of the pipe member is interposed between these brackets.
Further, according to the second patent document, the upper bracket of the pair of upper-and-lower brackets is provided with load input faces which are arranged to face to inward-side side walls of tunnel side members (tunnel side member inner wall faces) which are arranged both sides, in the vehicle width direction, of the floor tunnel portion such that when a load is inputted, the load is inputted from the tunnel side member inner wall faces to the upper bracket.
Further, the lower bracket of the pair of upper-and-lower brackets is provided a fixation portion which is configured to contact the lower faces of the tunnel side members and be fixedly fastened to the tunnel side members with bolts and nuts.
In the vehicle-body floor portion structure of the above-described second patent document, however, the above-described fixation portion is provided at another face different from the load-input face, and the load-input face and the tunnel side member inner wall face are not fixed directly despite their receiving the large collision load. Moreover, the lower bracket is configured to be fixedly fastened such that the fixation portion contacts the lower face of the tunnel side member at a single point only.
Therefore, there is a concern in the vehicle-body floor portion structure of the second patent document similarly to the floor structure of the automotive vehicle of the first patent document that the facing face portions slide improperly when receiving the large load, such as the collision load, so that there is room for improvement in order to achieve the smoother load transmission at the lower portion of the floor tunnel (floor tunnel portion).